In recent years extensive evidence has been accumulated indicating that catecholamines and adrenergic receptors importantly modulate many kidney functions. The major objective of this research program is to investigate in depth the kidney adrenergic receptors and their regulation in health and disease. The study is divided into three major sections. In Section I, high-affinity radiolabel binding techniques will be used to identify and quantify the beta- and alpha-adrenergic receptors and their subtypes in isolated rat kidney glomeruli and tubules. The binding will be correlated with various functional activities. In Section II, cation (sodium, magnesium) regulation and homologous (catecholamines and other adrenergic agents) regulation of the adrenergic receptors in glomeruli and tubules will be studied. In Section III, heterologous regulation (regulation by factors that normally do not interact with the adrenergic receptors) of the adrenergic receptors in glomeruli and tubules will be studied. Preliminary findings indicate that bilateral adrenalectomy markedly alters adrenergic receptors in the kidney. This effect, which is possibly secondary to alteration in adrenal steroids, will be studied in detail. The study will provide important insights into the regulation and functioning of kidney adrenergic receptors in health and disease.